In the related art, as a hydraulic pump, a variable displacement pump in which a discharge amount of a pump is made variable by changing an inclination angle of a swash plate has been known. For example, the following Patent Literature 1 discloses a variable displacement pump which includes a rotary shaft, and a cylinder block connected to the rotary shaft to integrally rotate, and has pistons housed to be reciprocally movable in a plurality of bores formed in the cylinder block. Further, in the variable displacement pump described in Patent Literature 1, the rotary shaft is supported with respect to a casing via a pair of tapered roller bearings. In such a variable displacement pump, in order to ensure the bearing life expectancy of the tapered roller bearing which supports the rotary shaft, usually a preload applying member such as a disc spring is inserted between a receiving part of the shaft and the bearing, thus applying preload to the tapered roller bearing.